The present invention relates generally to plows and more specifically to a lift linkage for a plow.
The typical drawn or towed plow is supported on front and rear furrow wheels and on a land wheel located forwardly of the rear furrow wheel. The plowing depth is conventionally controlled by adjusting the land wheel and the front furrow wheel. Such a plow is shown, for example, in U.S. Pat. No. 3,731,749.
Typical of previous plows, a hydraulic cylinder is directly connected to the ground wheel. The furrow wheel is vertically adjusted by the cylinder through a linkage which includes a lost motion connection. A cylinder having an adjustable stop for setting the plowing depth is commonly required and is more expensive than conventional cylinders.
Often in the case of conventional drawn plows, when the wheels are raised so that the plow enters the ground, the frame lowers in the approximate plowing attitude. Better and faster ground penetration can be achieved by slightly rolling or tilting the plow frame towards the landwheel so the point of each of the plow shares angles downwardly and enters the ground before the remainder of the share contacts and penetrates the soil. Although numerous lift linkage and hydraulic systems have been devised to adjust the rear furrow wheel with respect to the ground wheel, none have heretofore provided a satisfactory mechanism for tilting the plow frame while it is being lowered so that ground penetration is enhanced.